A data storage system, such as disk drive, generally includes one or more magnetic disks which are rotated by a spindle motor at a constant speed, and one or more information storage heads (generally called “sliders”) flying on the magnetic disk(s) to write data information to or read data information from the magnetic disks. The slider includes a bearing surface, such as an air bearing surface (ABS), which faces the disk surface. When the disk rotates, the air pressure between the disk and the ABS increases, which creates a hydrodynamic lifting force that causes the slider to lift and fly above the disk surface.
As is well known in the art, each of the sliders is mounted on a suspension which is supported by a drive arm (the suspension with the slider is generally called “head gimbal assembly”, which is abbreviated to “HGA”). The drive arm is movable and controlled by a voice coil motor (VCM). However, a flying height (FH) of the slider is easy to vary due to the following reasons: 1. the high-speed rotation of the disk; 2. the tolerance of air bearing surface (ABS) of the slider; 3. the static attitude of the suspension. The variation of the flying height will greatly influence the performance of the disk drive. That is, if the flying height is too high, it will affect the slider reading data from or writing data to the disk; on the contrary, if the flying height is too low, the shock of the slider may scratch the disk so as to cause the damage of the slider and/or the disk. In today's disk drive industry, with the rapid increase of disk drive's capacity, the track pitch and the track width of disk drive become narrower and narrower, and accordingly the flying height of the slider becomes lower and lower, so controlling the dynamic flying height of the slider becomes more and more important.
To achieve the above-mentioned requirement, U.S. Pat. No. 5,611,707 discloses an apparatus for controlling the dynamic flying height of the slider. Referring to FIG. 1, a disk drive comprises a magnetic disk 100 which rotates at a high speed about a spindle motor 110, and a head gimble assembly (HGA) 120 having a slider flying on the magnetic disk 100. A flying height controller 130 for controlling the dynamic flying height is mounted on the HGA 120. Referring to FIG. 2, the flying height controller 130 is consisted of a base 131 and a movable aerodynamic element 132. The movable aerodynamic element 132 can pivot about an edge 135 between the base 131 and the movable aerodynamic element 132. The movable aerodynamic element 132 can move from a closed position substantially parallel to the base 131 to an open position substantially perpendicular to the base 131. When in the closed position, the fly height controller 130 does not affect the control of flying height. While in the open position, the fly height controller 130 will depress the HGA 120 and accordingly reduce the flying height of the slider.
However, the flying height adjustment capability of the flying height controller 130 have a limitation, that is, it can only reduce the flying height, but can not increase the flying height. Actually, it is required to increase the flying height to compensate the fabrication variation of the slider and the HGA. In addition, because the flying height controller 130 is mounted on the HGA, it will increase the weight of the HGA and greatly influence the performance of the HGA 120, such as the resonance and the shock performance. Also, since the flying height controller 130 is far away from the slider, its adjustment accuracy is rather limited. Finally, because the flying height controller 130 has a complex structure, so it is rather costly and takes much time to manufacture such a flying height controller 130.
Hence it is desired to provide a method and system of adjusting flying height, and a HGA and disk drive which can overcome the foregoing drawbacks of the prior art.